Pu pi lo meter



(No Model.)

L. BURT.

PUPILOMETER.

No. 331,226, Patented NOV.'24. 1885.

WITNESSES N. PETERS. Phewuma m w. Wfllhinglum o. a

NITED STATES LOU BURT, OF DETROIT, MICHIGAN, ASSIGNOR TO JULIUS KING, OFCLEVE- LAND, OHIO.

PU Pl LO IVI ETE R.

SPECIFICATION forming part of Letters Patent No. 331,226, dated November24, 1885.

Application filed April '7, 1885. Serial No.16lA42. (No model.)

To all whom it may concern.-

Be it known that I, LOU BURT, of Detroit, in the county of WVayne andState of Michigan, have invented certain new and useful Improvements inPupilometers; and I do hereby declare the following to be a full, clear,and exact description of the invention, such as will enable othersskilled in the art to which it pertains to make and use the same.

My invention relates to pupilometers, the object being to provide aninstrument for accurately measuring the distance from center to centerof the pupils of the eyes, to the end that spectacle-lenses may becorrespondingly adjusted in the bows.

With this object in view my invention consists in certain features ofconstruction and in combination of parts hereinafter described, andpointed out in the claims.

In the accompanying drawings, Figure 1 is a view in perspective, showingthe manner of operating my improved pupilometer. Figs. 2 and 3 are planviews showing, respectively, the front and back sides of the instrument,but with the handle broken away.

A represents a thin plate, usually of metal, and preferably of about theform shown, constituting the body of the instrument, and provided with ahandle, A. The plate is cut away at a, and the edge bent upward to adaptit to fitastridethe nose. The plate has the slots a and a in line witheach other and with the handle, and the slots a in line with each other,but at right angles with the line of the slits a and a. A slight'slidingbar, B, has a thumbpiece, B, secured on top, and the rivet b, thatsecures the latter, passes through and operates in the slot a. At theopposite end the bar B has a stud, b, that passes through the slot a andhas attached at the rear and next the plate A a washer, O, and outsideof the .washer a slight cross-bar, c. To this cross-bar, and at equaldistances from the center thereof, are pivoted the connecting-rods E,that are of equal length, and are respectively pivoted to sliding blocksor studs 6, that operate in the slots a These sliding blocks in fronthave respectively attached pointers F, that extend about flush with theedge of the plate A. By means of the connections shown, when the bar B,by means of the thumb-piece, is moved toward or from the handle, thepointers F are made to approach or recede from each other, movingsimultaneously and equal distances. The plate B is provided with thepoints g, and the plate A with scales G and G, arranged so that thepointsg indicate in inches on the one scale and in millimeters on theother scale the distance between the pointers F.

In operating the instrumentitis placed in the position shown in Fig. 1and pressed slightly upon the nose to steady the instrument, and thepatient is directed to look straight ahead. By moving the thumb-piece Bthe pointers F are brought, respectively, directly under the center ofthe pupil of each eye. The adjustment requires but a moment, and whenthe instrument is removed an accurate measurement is retained,tl1atenables the operator to properly adjust the lenses from center to centerin the spectacle-bows. The slots a and a may be connected to form acontinuous slot, and the cross-bare may be dispensed with, if preferred,and the rods E pivoted one above the other on the stud b.

The instrument is simple, accurate, and in every way desirable for thepurposes specified.

WVhat I claim is- 1. A pupilometer consisting, essentially, of asuitable supporting-plate and adjustable pointers that may be placed injuxtaposition to the eyes, a thumb-piece, and suitable connectingmechanism for moving the pointers simultaneously and equal distancestoward or from each other, substantially as set forth.

2. In a pupilometer, the combination, with a plate arranged to fitastride the nose, and adjustable pointers arranged tooperate in front ofthe eyes, of a sliding thumbpiece and suitable connecting mechanism forsimultaneously 0 moving the pointers equal distances toward or from eachother, a scale, and index for noting the position of the pointers,substantially as set forth.

In testimony whereof I sign this specifica- 5 tion, in the presence oftwo witnesses, this 1st day of April, 1885.

LOU BURT.

Witnesses:

GEO. W. MOORE, M. P. HURLBUT.

